1. Field of the Invention
The present invention relates generally to a method of manufacturing a bump-component mounted body in which a bump component such as a flip chip, a chip size package (CSP), or the like can be mounted on a circuit board with a high yield and to a device for manufacturing the same.
2. Related Background Art
Recently, a flip chip mounting method has been receiving much attention as a method of mounting a semiconductor chip. In this method, bumps of electrical conductors are formed on pads (electrode terminals) of a bare semiconductor chip and the bumps and corresponding electrodes on a circuit board are electrically connected. Recently, this technique has been developed considerably since it enables a semiconductor chip to be mounted compactly and provides suitability for a high speed operation because of shortened wiring, as compared to the case of packages with leads such as a conventional quad flat package (QFP). Among flip-chip mounting techniques, mounting by stud bump bonding has high reliability and has come into practical use. In addition, a method of sticking a bare semiconductor directly on a circuit board with solder balls also has been known for many years.
The stud bump bonding method is described in xe2x80x9cAdvanced Flip Chip Bonding Technique for MCM-Lxe2x80x9d by Yoshihiro Tomura et al., 1996 Proceedings of First Pan Pacific Microelectronics Symposium, p 125-131 (1996).
CSPs and ball grid arrays (BGA) also are used often since they allow considerable size reduction to be achieved as compared to conventional quad flat packages (QFP). They also have bumps (solder balls) arranged in a plane and therefore, are included in bump components defined in the present invention.
The above methods have been employed widely but have a big problem.
There is no problem when a circuit board is always flat and is not deformed in mounting bump components. However, a general circuit board formed of a composite including, for example, a reinforced core material such as glass fiber or aramid fiber, resin, and copper foil is deformed due to heat inevitably added thereto for melt-bonding of solder balls in mounting bump components or curing of an underfill. Therefore, it is difficult to maintain the flatness of the circuit board. Particularly, when the circuit board is thin and is one such as a flexible circuit board, it can be said that it is substantially impossible to maintain the flatness of the circuit board.
As a method for solving this problem, there is a method in which a circuit board is pressed down together with a semiconductor chip during heating (for instance, an anisotropic conductive film (ACF) is interposed between a semiconductor chip and a circuit board, which then is heated while being pressed). In such a method, however, products inevitably must be processed one by one and thus, the productivity is low.
The present invention is intended to solve the above-mentioned conventional problem and to provide a method and device for manufacturing a bump-component mounted body allowing a circuit board to be prevented from being deformed due to heat added in mounting bump components.
In order to achieve such an object, the present invention employs the following configurations.
A first method of manufacturing a bump-component mounted body of the present invention includes pressing down a plurality of bump components mounted on a circuit board by a pressure difference provided between inner and outer sides of a flexible separation wall provided to cover the plurality of bump components.
According to this method, it is possible to compel a circuit board to maintain the flatness continuously during heating or other steps in which the deformation may possibly occur and thus the decrease in yield due to the deformation of the circuit board can be prevented.
A second method of manufacturing a bump-component mounted body according to the present invention includes at least injecting an underfill into a space inside a flexible separation wall during or after depressurizing the space inside the flexible separation wall. The space inside the flexible separation wall is formed between a circuit board and the flexible separation wall. The flexible separation wall is provided to cover bump components mounted on the circuit board. This method allows the space inside the flexible separation wall to be filled with the underfill at a high speed with no bubbles being contained.
A third method of manufacturing a bump-component mounted body according to the present invention includes: flip-mounting a plurality of bump components on a circuit board; forming a space inside a flexible separation wall between the flexible separation wall and the circuit board by covering the plurality of bump components with the flexible separation wall; and pressing the bump components against the circuit board by providing a pressure difference between inner and outer sides of the separation wall. This allows the circuit board to be maintained in a flat state continuously during a heating step carried out subsequent to the pressing and steps in which deformation may possibly occur, and thus the mounting yield increases. In addition, this method merely utilizes the pressure difference provided between the inner and outer sides of the separation wall and thus can be carried out at low cost.
The third method further may include, before the flip-mounting, applying a conductive adhesive to bumps of the bump components or to electrodes on the circuit board, and after the pressing of the bump components against the circuit board, drying, curing, or melting the conductive adhesive with the bump components being pressed against the circuit board, injecting an underfill into the space inside the separation wall during or after depressurizing the space inside the separation wall, and curing the underfill. According to this method, a flip-chip mounted body obtained by stud bump bonding can be produced with high yield. In addition, once the bump components are covered with the separation wall, the subsequent steps can be carried out with the separation wall covering the bump components until curing of the underfill is completed.
Furthermore, the third manufacturing method further may include, after the pressing of the bump components against the circuit board, melting solder bumps with the bump components being pressed against the circuit board. The solder bumps are provided on the bump components. According to this method, a flip chip mounted body in which bump components provided with solder balls are mounted can be obtained with high yield.
The third method further may include, after the pressing of the bump components against the circuit board, drying, curing, or melting an adhesive with the bump components being pressed against the circuit board, wherein the adhesive may be provided between the bump components and the circuit board in the flip-mounting. According to this method, a flip-chip mounted body in which an adhesive such as an ACF, an anisotropic conductive paste (ACP), a non-conductive paste (NCP) or the like is used can be obtained with high yield.
The third manufacturing method further may include cutting the circuit board. According to this, for example, a number of small card-type substrates (such as modules, CSPs, BGAs, or the like) with bump components mounted thereon can be manufactured at one time.
In the third manufacturing method, a sheet-like member may be provided between the bump components and the separation wall. According to this method, the separation wall can be prevented from being soiled or the separation wall and the bump-component mounted body can be separated easily. Alternatively, a sheet-like member can be integrated with the completed flip-chip mounted body to be used as an outer package of the flip-chip mounted body.
A device for manufacturing a bump-component mounted body of the present invention includes a supporting substrate on which a circuit board is placed, a flexible separation wall, a separation wall supporter for maintaining the separation wall, and a hermetic space (a space outside the separation wall) formed between the separation wall and the separation wall supporter. According to this device, a pressure difference between the inner and outer sides of the separation wall can be provided easily. Therefore, the above-mentioned manufacturing method of the present invention can be implemented with a simple configuration at low cost.
In the above-mentioned manufacturing device, preferably a space inside the separation wall is formed hermetically by the separation wall and the circuit board when the separation wall supporter maintaining the separation wall and the supporting substrate are combined with the circuit board being interposed therebetween. This allows the circuit board to be pressed against the supporting substrate upon providing the pressure difference between the hermetic space (the space outside the separation wall) and the space inside the separation wall and thus the circuit board is prevented from being deformed. In addition, the space inside the separation wall can be utilized as a mold in injecting an underfill.
Preferably, the above-mentioned manufacturing device further includes a rubber plug into which a pressurization pipe is to be inserted. The pressurization pipe is used for pressurizing the hermetic space defined by the separation wall and the separation wall supporter. According to this, a needle pipe can be inserted into the rubber plug and the hermetic space (the space outside the separation wall) can be pressurized easily. In addition, the pressurized state can be maintained even after the needle pipe is removed after the pressurization.
Preferably, the above-mentioned manufacturing device further includes a rubber plug into which a depressurization pipe for depressurizing the space inside the separation wall is to be inserted. According to this, a needle pipe can be inserted into the rubber plug and the space inside the separation wall can be depressurized easily. In addition, the depressurized state can be maintained even after the needle pipe is removed after the depressurization.
Preferably, the above-mentioned manufacturing device further includes a rubber plug into which an injection pipe is to be inserted. The injection pipe is used for injecting an underfill into the space inside the separation wall. According to this, a needle pipe can be inserted into the rubber plug and the underfill can be injected into the space inside the separation wall. In addition, the pressure difference between the inner and outer sides of the separation wall can be maintained even after the needle pipe is removed after the injection of the underfill.
Furthermore, in the above-mentioned manufacturing device, preferably the supporting substrate urges the circuit board into close contact therewith and maintains the circuit board. According to this, before the separation wall supporter and the supporting substrate are combined, the circuit board can be maintained in a flat state. Even when the hermetic space (the space outside the separation wall) is not pressurized sufficiently in injecting the underfill, the deformation of the circuit board can be prevented.
In the above-mentioned manufacturing device, it is preferable that when the separation wall supporter maintaining the separation wall and the supporting substrate are combined with the circuit board being interposed therebetween, part of the wiring of the circuit board is exposed. According to this, electrical testing can be carried out using the exposed wiring without the separation wall supporter being removed.